Performance improvement versus Directory/Extent fragmentation

[Rui Vilao]

Greetings,

I have Online JFS installed on a K server running HP-UX 10.20.

Here is the Fragmentation Report of 7var:

# fsadm -F vxfs -E -D /var

Directory Fragmentation Report
Dirs Total Immed Immeds Dirs to Blocks to
Searched Blocks Dirs to Add Reduce Reduce
total 4343 2716 3266 23 29 895

Extent Fragmentation Report
Total Average Average Total
Files File Blks # Extents Free Blks
18221 46 1 186493
blocks used for indirects: 296
% Free blocks in extents smaller than 64 blks: 17.71
% Free blocks in extents smaller than 8 blks: 5.32
% blks allocated to extents 64 blks or larger: 82.43
Free Extents By Size
1: 747 2: 685 4: 1950 8: 614
16: 515 32: 311 64: 276 128: 153
256: 106 512: 72 1024: 39 2048: 6
4096: 0 8192: 0 16384: 0 32768: 0


I never performed any de-fragmentation... What kind of performance improvement
can I expect in running "fsadm -F vxfs -d -D -e -E /var" ?

I am considering to create a script to do this periodically. How often shall I
run it and for which directories (all vxfs dirs?)?

Thanks in advance for your help!

Kind Regards,

Rui.

[Ng Oon Tian]

According to the docs

You are fine if:

If <8 blocks is less than 1% free space

less than 5% free space in <64 blocks

more than 5% of total filesystem size is available as free extents in length of 64 or more blocks.

You are not ok if

> 5% free space in <8 blocks
> 50% free space in <64 blocks
less than 5% of file system size avialable as free extents in 64 or more blocks.